﻿<p><em>IfcSurfaceStyleLighting</em> is a container class for properties for calculation of physically exact illuminance related to a particular surface style.</p>

<p>Figure 2 shows the reflection and transmission components from an incident ray. The sum of the components for reflection and transmission is a value of 1.0 denoting that the incident ray is completely decomposed into reflection and transmission components. Each value of reflection and transmission is therefore within the range 0.0 to 1.0.</p> 

<table>
<tr><td><img src="../../../figures/ifcsurfacelightingproperties_fig1.gif" alt="material reflection components" width="300" height="236" border="0"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Surface style lighting</p></td></tr>
</table>

<p>All these factors can be measured physically and are ratios for the red, green and blue part of the light. These properties are defined in the model as Type <em>IfcColorRGB</em> with a factor for each colour.</p> 

<blockquote class="example"> 
EXAMPLE&nbsp; A green glass transmits only green light, so its transmission factor is 0.0 for red, between 0.0 and 1.0 for green and 0.0 for blue. A green surface reflects only green light, so the reflectance factor is 0.0 for red, between 0.0 and 1.0 for green and 0.0 for blue.
</blockquote> 

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
</blockquote>
